(1) Field of the Invention
The present invention is directed to a method and apparatus for renewing a roof system. In particular, the apparatus of the present invention is used to prepare laminate roof systems for subsequent recovering by reducing the moisture content of the roof system. The method of the present invention includes both preparing and recovering the roof system.
(2) Description of the Related Art
There are many types of roof systems upon which the present invention may be used, however the invention is best suited for renewing various types of roof systems which typically cover commercial buildings. These commercial roof systems generally have a laminate construction, typically comprising a roof deck, an insulation material and a covering. The roof deck usually forms the bottom layer of the laminate roof system. The deck rests on joists which span the building and provide the majority of the structural support for the roof system. Typically, either steel sheets, composite wood panels, or solid wood boards are laid across the joists to form the roof deck. The insulation material is generally placed atop the roof deck and provides both thermal and acoustic insulation between the interior and exterior of the building. The covering is the top most layer of the typical laminate commercial roof system and may be tar, elastomeric sheet or any one of several other coverings which are well known in the art. The covering protects the roof deck and insulation material from the elements and prevents rainwater, melting snow and other moisture from penetrating the roof system. Thus, the covering keeps both the roof system itself and the interior of the building under the roof system dry.
Over time, due to the corrosive effects of the environment, as well as the deteriorative effects of ultraviolet radiation from the sun, the covering breaks down and permits moisture to penetrate into the roof system. If left unrepaired, the moisture will collect within the roof system and will ultimately drip into the interior of the building. Particularly corrosive environments may accelerate the deterioration of the covering. For instance, when the covering is used on roof systems in the vicinity of various chemical and manufacturing plants, the vapors exhausted from the plants can come in contact with the covering and cause the covering to deteriorate at an accelerated rate. Another common example of a particularly corrosive environment occurs on roof systems used to cover restaurants. The grease and oils emitted from fryers and grills during food preparation are usually exhausted to the roof of the restaurant where they collect and attack the roof system covering. Each of these particularly corrosive environments accelerate the degradation of the covering and thus shorten the serviceable life of the roof system by permitting moisture to penetrate the covering earlier than would otherwise occur. No matter which mode of attack occurs, when moisture penetrates the covering, the moisture is absorbed by the insulation material, and if the roof deck is made of wood, the moisture will be absorbed by the deck as well.
Most insulation material provides thermal insulation by pockets of stationary air held within voids formed in the material. These air pockets are highly resistant to the transfer of heat, but when moisture penetrates the insulation material, it displaces the air held in the voids. Because water has a lower thermal resistance than air, the penetration of the water reduces the thermal resistance of the insulation material and permits more heat transfer to occur through the roof system. As the transfer of heat through the roof system increases, the energy consumption required to heat and cool the building also increases. In addition, the increased moisture content provides a damp environment which fosters the growth of bacteria, mold and fungus, as well as many other undesirable plants and animals in and around the roof system. Further, moisture held in the insulation material accelerates the deterioration of the roof fastening or bonding system which holds the insulation material and covering to the deck and the deterioration of the roof deck, be it wood or steel.
In order to prevent the undesirable consequences of moisture penetration, a roof system must be repaired or replaced periodically. When a roof system is repaired or replaced, it is typically covered with a new covering to prevent moisture from penetrating into the insulation material and roof decking. In the past, if moisture had penetrated the insulation material and/or roof decking, the wetted roof system components such as the insulation material and roof deck had to be replaced prior to recovering the roof system. This additional step significantly increased the cost of repairing the roof system due to additional material and installation expenses.
Further, when the roof system components are replaced, they are generally disposed of in a landfill or other solid waste disposal site. However, there is a growing concern regarding the environmental impact of discarding what is perceived as being a large volume of solid waste. Thus, disposal of used roof system components has the potential to raise public concern. In addition, waste disposal adds cost to the replacement of roof systems because solid waste disposal sites charge for use of their facilities.
Some insulation materials which were commonly used in the construction of roof systems in the past have been found to present health hazards. In particular, asbestos has been found to cause asbestosis and other detrimental health effects when humans breath airborne asbestos fibers. Thus, if asbestos is present in the insulation material of the roof system, disturbing it during repair presents a health risk. Although there are methods for containing the airborne fibers, the cost associated with these methods further increases the cost of repairing the roof systems. Thus, it is preferable to leave roof system components in place during repair. However, in the past when moisture had penetrated the roof system components, leaving the components in place was not advisable for the reasons given above.
One other consideration must be taken into account when roof systems are repaired. Roofs must withstand loads caused by snow, wind and other types of indigenous environmental loads which are well known in the art, as well as loads due to saturation of the insulation material and roof deck. The joists which support the roof system provide a majority of the structural support to withstand these loads. The joists also provide most of the support to hold up the roof system itself. Thus, if the weight of the roof system is increased, the magnitude of the environmental loads which the joists can withstand is reduced because the strength of the joists is constant. Therefore, increasing the weight of the roof system during repair is undesirable.